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Evaluating roadway subsurface drainage practices – phase II.

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English


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  • Abstract:
    Well-performing subsurface drainage systems form an important aspect of pavement design by the Iowa Department of

    Transportation (DOT). The recently completed Iowa Highway Research Board (IHRB) project TR-643 provided extensive

    insights into Iowa subsurface drainage practices and pavement subdrain outlet performance. However, the project TR-643 (Phase

    I) forensic testing and evaluation were carried out in a drought year and during the fall season in 2012. Based on the findings of

    IHRB Project TR-643, the Iowa DOT requested an expanded Phase II study to address several additional research needs: evaluate

    the seasonal variation effects (dry fall 2012 versus wet spring/summer 2013, etc.) on subdrain outlet condition and performance;

    investigate the characteristics of tufa formation in Iowa subdrain outlets; investigate the condition of composite pavement

    subdrain outlets; examine the effect of resurfacing/widening/rehabilitation on subdrain outlets (e.g., the effects of patching on

    subdrain outlet performance); and identify a suitable drain outlet protection mechanism (like a headwall) and design for Iowa

    subdrain outlets based on a review of practices adopted by nearby states.

    A detailed forensic test plan was developed and executed for inspecting the Iowa pavement subdrains in pursuit of fulfilling the

    Phase II study objectives. The observed outlets with blockage and the associated surface distresses in newly constructed jointed

    plain concrete pavements (JPCPs) were slightly higher during summer 2013 compared to fall 2012. However, these differences

    are not significant. Less tufa formation due to the recycled portland cement concrete (RPCC) base was observed with (a) the use

    of plastic outlet pipe without the gate screen–type rodent guard and (b) the use of blended RPCC and virgin aggregate materials.

    In hot-mix asphalt (HMA) over JPCP, moisture-related distress types (e.g., reflection cracking) were observed more near blocked

    drainage outlet locations than near “no blockage” outlet locations. This finding indicates that compromised drainage outlet

    performance could accelerate the development of moisture-related distresses in Iowa composite pavement systems.

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    urn:sha-512:e96b99caec92e1284c1c335769154bf1e72c802f16452c5bed2adae59c3c88d417652520d4dde41782bc3c43f9b823bdba6963d38125c59d83336c7465988971
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File Language:
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